blower + turbo thread
 

can you guys take a look at this thread and give me your thoughts on my thinking http://forum.miata.net/vb/showthread...6&page=1&pp=25

basically they are talking about having a pos. disp. blower as well as a turbo on a miata or whatever little 4 cyl motor they can find...I basically said its kinda ricey & I dont see the point to it and would assume that the blower at some point would become a restriction. I dont know if it would or not but that was my thinking, maybe someone with more knowledge would be able to fill me in...I'd just like a second opinion.

Well, the first thing would be that the turbo would be taking hot exhaust gas and forcing it into a supercharger that will be using that hot gas to mix with cold fuel and compressing it. One of the keys to making more power is a cool dense charge. With too much boost on the turbo the first thing would be an uneven a/f ratio. The second would be the fact that you'd have to run two seperate intercoolers, the first for the turbo beeing of massive size and the second for the charger, neither of which would even fit in a Miata and if by some miracle you DID get them to fit, you've just added a ton of weight. The next obsticle would be the fact that a turbo and a charger have way different peak rpms. The turbo can spin much higher than the charger. If my thinking is correct, you'd have to run a small fast spooling turbo to get low end power but the charger will peak out around 5600 anyway. With the size and weight of a Miata you don't need that kind of low end TQ, the car won't be able to put it down effectively so you'd in effect be running a turbo for no reason other than to add weight, increase the intake charge temp, and completely make a mess out of your power curve. A big factor is what type of charger he wants to run. A roots is out of the question, peak rpm is too low. Centrifugal maybe, but the point still remains, why feed a supercharger hot gas that will have a varying temp and density/pressure? Think about it, turbos have a power band that ramps up over time with boost pressure changing. A charger has to be set up for a certain a/f mix and with that kind of air change, you'd probably have to have a computer actively adjusting fuel flow, hence, more weight. Miata's are small, light weight cars. What you probalby don't want is gobs of low-end TQ. I'd say throw a decent turbo on it and be done with it.

were talking say a T3 turbo & an eaton type blower and having the eaton @ 4psi dump so it doesnt make any boost...they are basically just talking for low end ie 1000-3000rpms and then it starts dumping the boost & running souly on the turbo...Im like ok so for that .2 second your at that rpm in 1st gear off idle that would work great but otherwise its pointless & just get a properly sized turbo and be done with it....or get an auto with a properly sized converter & be done with it lol. Notice the responses about they dont know about automatic in miatas though...see what my wife has done to me guys? I've already got like 60 posts on there, SAVE ME PLEASE!!!

HAHA. Miata people are dumb....well, not you, but everyone else that thinks twincharging is a "great" idea. Of course the blower is gonna become a restriction at one point or another. If it wasnt, then people could just pop the belt off their superchargers and run around like that to save gas, then when they go to the strip, throw the belt back on :roll: . Bill, you are dead on, I can't even understand where everyone elses thinking is coming from

Edit

Its also not such a great idea because you'd be wasting all kinds of power just spinning the supercharger. If they want instant power, get a supercharger, if they want more efficent power with the slight possibility of lag, get the turbo.

That's just retarded. The blower will peak out before the turbo can really show it's stuff and the motor will be under peak rpm as well. They need to know that even if the charger is dumping the boost, it still has a max rpm limit of about 5600 on a conventional roots system and the larger the cubic displacement of the blower to allow a higher rpm, the higher the power curve comes in so it's a catch 22. That's why Top Fuel cars run 14-71 mag cased high-helix blowers and destroked motors, they both hit at the same time. Why try and get massive low end TQ when a Miata can't even put it down effectively. A Miata doesn't need low end TQ, it has no weight on the rear end. If they want tons of power, stroke the motor and throw a charger on it. If they want high reving power over a wide band, use the turbo. The effective power bands and peak rpms coupled with the intake charge density and temp characteristics negate the possibility of using the setup effectively, at least in a Miata. Say a truck with the room to house all that gear and the need for a ton of low end TQ without the need for a huge rpm redline might be where you could use something like that.

looks like someone's already putting the theory to the test:
http://brpforum.infopop.cc/eve/ubb.x...img/Y/SCTC.jpg

found here: miata forum - there's a movie there, too.

Jesus. Some people have way too much time and money on their hands. Hot intake charge from turbo going into charger via vacuum hose wrapped in seran wrap. Love those ghey bicycle horns too. Ricer.

wonder what the iat reading would be on a setup like that lol

wrong. a turbo uses the exhaust gases to spin an impeller that compresses the incoming intake air. it does NOT put exhaust gas back into the engine. the EGR system does that.

twincharging does have some benefits. the best setups i have seen are similar to twin-turbo setups. the supercharger is used for off-the-line power, and once the turbo spools up, it switches over to the turbo for high-RPM power. the supercharger uses a clutch to accomplish this.

twincharged systems are hard to tune, though. HKS makes a twincharging kit, which is top of the line, but even then, it's not easy to tune properly.

twincharging is extremely rare, and when done properly, can make heaps of power. it wouldn't be my first choice (i'd go with a twin-turbo or big single turbo) but it is unique, and will get you a lot of looks.

Oops, i R dumb. Anyway, I still think it sux :P

A proper turbo setup will overcome the low end lag and also be better on the top end. The supercharger will just get in the way and reduce flow at some point and add drag to the engine because of the belt. Either turbo it or supercharge it, not both. My cousin's husband runs his own repair garage doing mostly Honda stuff but he installed a supercharger setup on a customer's Miata and he said it ran pretty strong like that. There wasn't much room to work with, but then most of today's cars don't have any room in the engine compartment. Oh, and a turbo does transfer heat to the intake side to some extent. The setup in that picture is looking for trouble with a turbo pumping directly into a supercharger with no intercooler? Run away from that cr@p.

they posted new pics of the same system in the thread...its got an intercooler between the turbo & blower & hes using water injection after the blower lol I just dont see a point to all that work for a boost in low low end tq lol. And because of the design of a turbo your unintentionally heating the intake charge one way or the other...dpending on boost levels you could easily be pushing iats of 190F+ with no intercooler at all...so even though exhaust gas isnt being recirculated it still isnt "cool" air being pushed into the motor w/o an intercooler.

compressing air is what heats it up. using an intercooler reduces that heat. whether you use a supercharger or a turbocharger, you're still compressing the air and heating it up.

superchargers require a belt attached to the crank, which will require some horsepower to run it. the numbers are really low these days with the advances in supercharger architecture, but you'll still be drawing 1-3% horsepower to run the thing.

turbochargers use exhaust gas to run the turbine, so you're not taxing the system to run it. some of the heat from the exhaust gas, depending on where the turbo is located in the system, will get transferred to the intake charge just because of the proximity of the turbo to the origination of the exhaust, but the major amount of heat is caused by compression. some systems, like on the 4th gen that had the turbo in the rear where the muffler normally goes, reduces the temperature just because of how far the exhaust gas has to travel to get to the turbo, then how far the compressed air has to travel to get to the intake manifold. an intercooler on a system like that will reduce the temperature considerably, therefore allowing for greater amounts of power.

i don't understand the thought process behind having both types of systems on one vehicle. is he trying to reduce the tax on the system required to run the supercharger by supplementing it with turbo boost? is he trying to overcome the inherent turbo lag with boost from the supercharger? or is he just trying to be different? lag from the turbo is not quite as significant as it once was, so jump starting the system with the supercharger really doesn't make sense.

all I know is there's a guy in NJ w/ a twin charged mini running around that is set up pretty sweet, and Chevy is working with some company in CA(like SLP) that has twincharged the Cobalt SS.
http://www.mustangworld.com/forums/i...ncakebunny.gif

yeah i posted info about a twincharged mini & wrx in the thread & posted about hte cobalt ss here a few posts down.

yup...because its a 4 cyl theres going to be more lag one way or the other...but i remember test driving a new eclipse turbo back in the day & i just couldnt see myself adding a blower to that just to add a little low end tq :shrug:

sorry, this was the 1st post i read the AM, but I did give you a bunny w/ a pancake on it's head. that should count for something.



yeah, it's one of those days

GarretWP just bought a Mini Cooper S and he's been researching the turbo kit that works in conjunction with the stock Eaton blower. I don't know that many details about it, but it seems to put down some great numbers....

- Justin

that's a bunny with a turtle shell on his head. kind of like halloween.

yeah, yeah, whatever. it may look like a pancake, but it's really a turtle shell. you know, the story of the tortoise and the hare? why would a rabbit have a pancake on its head? it makes so much more sense that he's pretending to be the turtle with a turtle shell on his head, ala bugs bunny.

it jsut seems like a waste to use both. you can't put any more boost into a motor without blowing it up just because you have a blower + turbo.
keep it simple and just do a single turbo.
less tubing, less restriction, and less waste

later
tim

Bill, I replied in the actual thread.
I think it's a huge waste of money and stated the times when you would consider twincharging. Did you read my post?
There are times when it's benifitial, times when it isn't. For the street and normal fun driving I'd consider it a waste of money, but road racing, serious drag racing and rally, it might very well be worth it if your class limits you on displacement.

yah i read them...i love how they even try to question you...funny chit.

the rabbit having a pancake on it's head makes as much sense as twin-charging. :knock:
the set-up can be REAL nice, but doesn't justify the time/$$$ put into the project.